When a milk cow suffers from mastitis or milk fever, the deterioration of milk and the decrease of the quantity of secreted milk inflict heavy loss on the milk producer. Therefore, the early discovery of mastitis of the cow is important.
At present, the abnormal milk detection method being utilized most widely is the California Mastitis Test (CMT) or a modification of CMT.
The extent of a coagulation reaction caused when CMT reagent is added to the sample milk is judged by this method. This is to measure semiqualitatively the number of somatic cell (mainly leukocytes) included in the milk.
However, these test operations require experience, being defective in that the judgement is apt to be governed by subjective elements, the difference between individuals, or the physiological condition of the cow. Therefore a correct judgement cannot be done easily.
It is well known that mastitis and milk fever are diseases of mamma and in the milk drawn from a cow suffering from these diseases, the concentration of Na ion and Cl ion is abnormally high, increasing the electric conductivity of the milk.
According to the results of observation of values of ingredients analysed of milk from each quarter mamma, the ingredient of milk from each quarter mamma of the same udder of a healthy cow is the same, showing the same electric conductivity. However, in case the cow is suffering from mastitis it is scarcely observed that all milk from four quarter mammae are tainted and the ingredients of milk from all quarter mammae show abnormal values. The abnormality is usually restricted to some of the quarter mammae. This is because quarter mammae do not have the same sensitivity to various stimulations and a certain quarter mamma is more affected sensitively than other quarter mamma, being apt to suffer from the mastitis easily.
Accordingly, it is necessary to examine the milk drawn from each quarter mamma instead of the mixed milk from four quarter mammae and to measure the electric conductivity of the milk from each quarter mamma. The electric conductivity of the milk is varied not only by the disease, such as mastitis, but also by the difference of the individual cow, the cow's physiological condition, the season and the temperature. Therefore, by comparing the conductivity of respective milk drawn from the quarter mammae, the mastitis can be surely judged. At the same the extent of trouble existing in each quarter mamma can be ascertained.
The judging method by means of the electric conductivity measurement is to measure the specific electric conductivity of milk from four quarter mammae, obtaining the difference of the specific conductivity between the reference milk from a quarter mamma (the milk from the quarter mamma showing the minimum specific electric conductivity) and the milk from other quarter mamma. The milk showing a difference in value of the specific electric conductivity between the quarter mammae larger than the abnormal milk detection reference value is judged to be the milk drawn from an abnormal quarter mamma and the quarter mamma secreting such milk is judged to be suffering from the mastitis. The extent of disease is proportional to the difference in value between quarter mammae.
This method does not depend on any individual difference in the extent of coagulation of the milk to be examined, the observational distinction of tone of color and the like, compared with said CMT tester method which has been carried out. Thus this method is extremely effective because it is sharp in the examination sensitivity.
The electric conductivity measuring method, like the conventional CMT tester method, is inconvenient in that a certain fixed quantity of milk sucked from each quarter mamma must be sampled individually for the examination and only the state at a certain time point can be examined. Therefore a continuous examination cannot be done during the whole milking operation.
Generally, in the milking operation, milk secreted in each quarter mamma automatically drawn by a milking machine is mixed immediately. Therefore, the sampling is necessary to be done before the milking machine is fitted to the cow. Further, the state of the quality of milk changing during the operation of milking cannot be checked.
The object of the present invention is to check milk drawn from each quarter mamma automatically and continuously during the continuous milking operation by using the examination apparatus for milk from individual quarter mamma to effect electric conductivity measurement in the milking process.
Further, the object of the present invention is to indicate the extent of the quality of milk in multiple stages by dividing the output obtained through the mesurement into some groups.